Auto-calibration to a station of a process module that spins a wafer

ABSTRACT

A method for calibration including determining a temperature induced offset in a pedestal of a process module under a temperature condition for a process. The method includes delivering a wafer to the pedestal of the process module by a robot, and detecting an entry offset. The method includes rotating the wafer over the pedestal by an angle. The method includes removing the wafer from the pedestal by the robot and measuring an exit offset. The method includes determining a magnitude and direction of the temperature induced offset using the entry offset and exit offset.

CLAIM OF PRIORITY

This application is a continuation of and claims priority to and thebenefit of commonly owned U.S. patent application Ser. No. 16/000,734,filed on Jun. 5, 2018, entitled “AUTO-CALIBRATION TO A STATION OF APROCESS MODULE THAT SPINS A WAFER”. which claims priority to and thebenefit of the commonly owned, provisional patent application, U.S. Ser.No. 62/595,454, filed on Dec. 6, 2017, entitled “AUTO-CALIBRATION TO ASTATION OF A PROCESS MODULE THAT SPINS A WAFER,” all of which are hereinincorporated by reference in their entireties for all purposes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No.15/291,549, entitled “WAFER POSITIONING PEDESTAL FOR SEMICONDUCTORPROCESSING,” filed on Oct. 12, 2016.

TECHNICAL FIELD

The present embodiments relate to robots, and more particularly torobots employed in wafer processing systems.

BACKGROUND OF THE DISCLOSURE

In semiconductor processing systems, robots are employed to move wafersfrom one location to another. For example, one or more robots may beemployed to pick up a wafer from a wafer cassette in a loading port,move the wafer to a load lock, move the wafer to one or moreintermediate locations (e.g., transfer modules), and move the wafer to aprocess module or reactor for wafer processing.

To accurately place and pick up wafers, a robot needs to know thecoordinates of various locations in the wafer processing system.Coordinates may be programmed into a respective robot during a set-upprocess after it is installed in the wafer processing system. In thatmanner, hand-off (e.g., pick and place) locations used by the robot areknown. For example, a robot may be used to transfer wafers from atransfer module into a process module, such as to a pedestal center.Typically, the set-up process is performed by a technician or a fieldservice engineer while the process module is cold. However, once theprocess module is under vacuum or raised to a higher temperature,coordinates of a specific location (e.g., center of a pedestal) withinthe process module may have moved. Accurate placement of a wafer to aspecific location during process conditions is desired to decreaseerrors incurred during the processing of the wafer, and to achievesmaller form factors for semiconductor devices and/or integratedcircuits.

The background description provided herein is for the purposes ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description that may nototherwise qualify as prior art at the time of filing, are neitherexpressly nor impliedly admitted as prior art against the presentdisclosure.

It is in this context that disclosures arise.

SUMMARY

The present embodiments relate to solving one or more problems found inthe related art, and specifically to measure the offset of a specificlocation, such as a location tied to a device, within a process modulethat is under condition.

Embodiments of the present disclosure include a method for calibrationto include determining a temperature induced offset in a pedestal of aprocess module under a temperature condition for a process. The methodincludes delivering a wafer to the pedestal of the process module by arobot, and detecting an entry offset. The method includes rotating thewafer over the pedestal by an angle. The method includes removing thewafer from the pedestal by the robot and measuring an exit offset. Themethod includes determining a magnitude and direction of the temperatureinduced offset using the entry offset and exit offset.

Embodiments of the disclosure include a method for calibration. Themethod includes establishing a reference coordinate system based on aninitial calibrated location of a rotation axis of a rotation devicewithin a process module. The method includes applying a condition to theprocess module. The method includes picking up a calibration wafer froman inbound load lock using a transfer module (TM) robot configured totransfer the calibration wafer to the process module. The methodincludes determining a first measurement of the calibration wafer withinthe reference coordinate system using a measurement device whentransferring the calibration wafer to the process module, themeasurement device fixed within the reference coordinate system. Themethod includes handing off the calibration wafer to the process moduleusing the TM robot. The method includes interfacing the calibrationwafer with the rotation device. The method includes rotating thecalibration wafer by an angle using the rotation device. The methodincludes removing the calibration wafer from the process module usingthe TM robot. The method includes determining a second measurement ofthe calibration wafer within the reference coordinate system using themeasurement device when transferring the calibration wafer to anoutbound load lock. The method includes determining a conditioncorrection of the rotation axis based on the first measurement and thesecond measurement, the condition correction corresponding to the offsetof the rotation axis from the initial calibrated location when theprocess module is under the condition.

Embodiments of the disclosure include another method for calibration.The method includes establishing a reference coordinate system based onan initial calibrated location of a rotation axis of a rotation devicewithin a process module. The method includes establishing a calibratedreference measurement of a calibration wafer within the referencecoordinate system using a measurement device fixed within the referencecoordinate system when transferring the calibration wafer from theprocess module from the initial calibrated location using a transfermodule (TM) robot. The calibration wafer placed to be centered about therotation axis, such that the calibrated reference measurement is alignedwith the initial calibrated location of the rotation axis. The methodincludes determining a condition correction of the rotation axiscorresponding to an offset of the rotation axis from the initialcalibrated location when the process module is under a condition basedon a rotation of the calibration wafer by an angle about the rotationaxis using the rotation device within the process module. The methodincludes picking up a process wafer from an inbound load lock using theTM robot. The method includes determining an alignment measurement ofthe process wafer within the reference coordinate system using themeasurement device when transferring the process wafer to the processmodule. The method includes determining an alignment correction of aprocess wafer corresponding to an offset of the process wafer from thecalibrated reference measurement based on the alignment measurement. Themethod includes applying the condition correction to the process waferusing the TM robot. The method includes applying the alignmentcorrection using the TM robot to align the process wafer to the rotationaxis that is offset from the initial calibrated location.

Embodiments of the disclosure include a system for processing wafers.The system includes a process module including a rotation device havinga rotation axis. The system includes a reference coordinate system basedon an initial calibrated location of the rotation axis of the rotationdevice. The system includes a transfer module (TM) robot configured fortransferring wafers to and from the process module. The system includesa measurement device fixed within the reference coordinate system, themeasurement device intercepting wafers transferred to and from theprocess module. The system includes a processor and memory coupled tothe processor and having stored therein instructions that, if executedby the processor, cause the processor to execute a method forcalibration comprising. The method includes establishing a referencecoordinate system based on an initial calibrated location of a rotationaxis of a rotation device within the process module. The method includesapplying a condition to the process module. The method includes pickingup a calibration wafer from an inbound load lock using the TM robotconfigured to transfer the calibration wafer to the process module. Themethod includes determining a first measurement of the calibration waferwithin the reference coordinate system using a measurement device whentransferring the calibration wafer to the process module, themeasurement device fixed within the reference coordinate system. Themethod includes handing off the calibration wafer to the process module.The method includes interfacing the calibration wafer with the rotationdevice. The method includes rotating the calibration wafer by an angleusing the rotation device. The method includes removing the calibrationwafer from the process module using the TM robot. The method includesdetermining a second measurement of the calibration wafer within thereference coordinate system using the measurement device whentransferring the calibration wafer to an outbound load lock. The methodincludes determining a condition correction of the rotation axis basedon the first measurement and the second measurement, the conditioncorrection corresponding to the offset of the rotation axis from theinitial calibrated location when the process module is under thecondition.

These and other advantages will be appreciated by those skilled in theart upon reading the entire specification and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments may best be understood by reference to the followingdescription taken in conjunction with the accompanying drawings.

FIG. 1 illustrates a substrate processing system, which is used toprocess a wafer, e.g., to form films thereon.

FIG. 2 illustrates a top view of a multi-station processing tool and/orprocess module, wherein four processing stations are provided, inaccordance with one embodiment.

FIG. 3 shows a schematic view of an embodiment of a multi-stationprocessing tool with an inbound load lock and an outbound load lock, inaccordance with one embodiment.

FIG. 4A illustrates an incoming wafer to a multi-station process moduleshowing the orientation of the incoming wafer for purposes ofdetermining an offset of a rotation axis of a device within the processmodule that is under a process condition, in accordance with oneembodiment of the present disclosure.

FIG. 4B illustrates an outgoing wafer from the multi-station processmodule introduced in FIG. 4A showing the orientation of the outgoingwafer for purposes of determining an offset of a rotation axis of adevice within the process module that is under a process condition, inaccordance with one embodiment of the present disclosure.

FIG. 4C illustrates the process of determining an offset of a rotationaxis of a device within a process module that is under a processcondition using measurements of an incoming wafer and an outgoing wafer,in accordance with one embodiment of the present disclosure.

FIG. 4D illustrates an example of calculating an offset correctionvector, in accordance with one embodiment of the present disclosure.

FIG. 4E is a flow diagram illustrating a method for determining atemperature induced offset of pedestal in a process module that is undera process condition, in accordance with one embodiment of the presentdisclosure.

FIG. 5A is a flow diagram illustrating a method for determining acalibrated reference measurement (e.g., initialized location) of acalibration wafer held by a transfer module (TM) robot as measured by ameasuring device, wherein the location of the calibrated referencemeasurement is aligned with the initial calibrated location of arotation axis of a rotation device within a process module, inaccordance with one embodiment of the present disclosure.

FIG. 5B is a flow diagram illustrating a method for determining anoffset of a rotation axis of a rotation device located within a processmodule that is under a process condition using the calibrated referencemeasurement of the calibration wafer, in accordance with one embodimentof the present disclosure.

FIG. 5C is a flow diagram illustrating a method for determining analignment offset of an incoming process wafer from the calibratedreference measurement, and applying an alignment correction based on thealignment offset and a condition correction based on the offset of therotation axis to the incoming process wafer, in accordance with oneembodiment of the present disclosure.

FIG. 6A is a diagram illustrating the calibrated reference measurementof a calibration wafer that is aligned with the initial location of arotation axis of a rotation device within a process module, and theeffect that an offset of a rotation axis of a rotation device within aprocess module has on the calibration wafer when the calibration waferis rotated, in accordance with one embodiment of the present disclosure.

FIG. 6B is a diagram illustrating the determination of the offset of arotation axis of a rotation device within a process module by rotatingan incoming wafer by an angle by the rotation device, wherein thedetermination is alignment agnostic, in accordance with one embodimentof the disclosure.

FIG. 7 is a diagram illustrating the alignment offset of an incomingprocess wafer from the calibrated reference measurement, in accordancewith one embodiment of the present disclosure.

FIG. 8 shows a control module for controlling the systems describedabove.

DETAILED DESCRIPTION

Although the following detailed description contains many specificdetails for the purposes of illustration, anyone of ordinary skill inthe art will appreciate that many variations and alterations to thefollowing details are within the scope of the present disclosure.Accordingly, the aspects of the present disclosure described below areset forth without any loss of generality to, and without imposinglimitations upon, the claims that follow this description.

Generally speaking, the various embodiments of the present disclosuredescribe systems and methods that provide for correction of an offset ofa rotation axis of a rotation device (e.g., rotating pedestal) within aprocess module. In that manner, embodiments of the present disclosureare capable of reducing errors caused by misalignment of an incomingwafer that is delivered to a calibrated location (e.g., rotation axis)within a process module that has moved after a process condition hasbeen placed on the process module. By correcting for this conditionoffset, the form factor of the semiconductor devices and integratedcircuits including the semiconductor devices can be reduced.

With the above general understanding of the various embodiments, exampledetails of the embodiments will now be described with reference to thevarious drawings. Similarly numbered elements and/or components in oneor more figures are intended to generally have the same configurationand/or functionality. Further, figures may not be drawn to scale but areintended to illustrate and emphasize novel concepts. It will beapparent, that the present embodiments may be practiced without some orall of these specific details. In other instances, well-known processoperations have not been described in detail in order not tounnecessarily obscure the present embodiments.

Embodiments of the present disclosure relate to methods and apparatusesfor performing calibration of robots and/or tool systems coupled to aplasma process modules, such as those used in atomic layer deposition(ALD) and plasma enhanced chemical vapor deposition (PECVD) processes.Embodiments of the present disclosure may be implemented in variousprocess module configurations. Further, embodiments of the presentdisclosure are not limited to the examples provided herein, and may bepracticed in different plasma processing systems employing differentconfigurations, geometries, and plasma-generating technologies (e.g.,inductively coupled systems, capacitively coupled systems,electron-cyclotron resonance systems, microwave systems, etc.). Examplesof plasma processing systems and plasma process modules are disclosed incommonly owned U.S. Pat. Nos. 8,862,855, and 8,847,495, and 8,485,128,and U.S. patent application Ser. No. 15/369,110.

FIG. 1 illustrates a plasma processing system 100, which is used toprocess a wafer, e.g., to form films over substrates, such as thoseformed in ALD and PECVD processes. System 100 is configured to processwafers to produce semiconductor devices, for example. Front openingunified pods (FOUPs) (not shown) are configured for holding one or morewafers and for moving wafers into, within, and out of system 100. FOUPSmay interface with load port(s) 160 for delivery of wafers. Inparticular, a wafer may be transferred within a FOUP between anequipment front-end module (EFEM) 150 and a respective process module110 via a transfer module 190 during processing. Load ports 160 areconfigured for moving wafers to and from the EFEM 150 duringpre-processing and post-processing.

The EFEM 150 is configured for moving wafers between the atmosphere andvacuum (the processing environment of the PM 110). EFEM 150 isconfigured for moving wafers between the FOUP and the load-locks 170.Transfer robots 131 (e.g., robot arms and the like) transfer wafersbetween load ports 160 and appropriate load locks 170 along track 152.Various gate valves 180 in combination with load locks 170, transfermodule 190, and process module 110 may be employed to maintain or createappropriate pressures (e.g., atmosphere, vacuum, and transitions betweenthe two). Gate valves 180 are configured to isolate components duringmovement and/or processing of wafers, especially when wafers are exposedto various pressures in system 100. For instance, gate valves 180 mayisolate the EFEM 150, load locks 179, transfer module 190 and processmodules 110. Load locks 170 include transfer devices to transfersubstrates (e.g., wafers in FOUPs) from the EFEM 150 to the transfermodule 190. The load locks 170 may be evacuated under pressure beforeaccessing a vacuum environment maintained by the transfer module 190, ormay be vented to atmosphere before accessing the EFEM 150. For example,load locks 170 may be coupled to a vacuum source (not shown) so that,when gate valves 180 are closed, load locks 170 may be pumped down. Assuch, the load locks 170 may be configured to maintain a desiredpressure, such as when transferring wafers under vacuum pressure betweenthe load locks 170 and the transfer module 190, or when transferringwafers under atmospheric pressure between the load locks 170 and theEFEM 150.

The transfer module 190 is configured to transfer substrates (e.g.,wafers in the load locks 170) to and from the process modules 110 viagate valves 180. In one configuration, the gate valves 180 includecontrollable openings (e.g., access doors) allowing access to theadjacent modules (e.g., transfer module 190, EFEM 150, process module110, etc.). Within the transfer module 190, transfer robots 132 (e.g.,robot arms and the like) are configured to move process wafer 101 withinthe vacuum environment using track 133, such as transferring wafersbetween process modules 110, or to and from the load locks 170. Thetransfer module 190 and the process modules 110 typically operate undervacuum, and may be coupled with one or more vacuum source(s) (not shown)to maintain the appropriate vacuum pressure.

One or more process modules 110 may be coupled to the transfer module190. Each of the process modules 110 are configured to process wafers,or any suitable object requiring processing in a vacuum or othercontrolled environment. The process modules 110 may be a single stationor multi-station configuration. The depicted process module 110comprises four process stations, numbered from 1 to 4 in the embodimentshown in FIG. 1. For example, the process modules 110 may be configuredto implement one or more semiconductor manufacturing processes. In oneconfiguration, the process modules 110 include a plasma processingchamber. In general, the process modules 110 can rely on a variety ofmechanisms to generate plasma, such as inductive coupling (transformercoupling), helicon, electron cyclotron resonance, capacitive coupling(parallel plate). For instance, high density plasma can be produced in atransformer coupled plasma (TCPTM) processing chamber, or in an electroncyclotron resonance (ECR) processing chamber. An example of a high-flowplasma processing chamber or process module that can provide highdensity plasma is disclosed in commonly-owned U.S. Pat. No. 5,948,704.For illustration of chambers located in process modules, parallel plateplasma processing chambers, electron-cyclotron resonance (ECR) plasmaprocessing chambers, and transformer coupled plasma (TCPTM) processingchambers are disclosed in commonly-owned U.S. Pat. Nos. 4,340,462;4,948,458; 5,200,232 and 5,820,723.

FIG. 2 illustrates a top view of a multi-station processing tool orprocess module 110, wherein four processing stations are provided. Thistop view is of the lower chamber portion 102 b (e.g., with a top chamberportion removed for illustration), wherein four stations are accessed byspider forks 226. Each spider fork, or fork includes a first and secondarm, each of which is positioned around a portion of each side of apedestal 140. In this view, the spider forks 226 are drawn indash-lines, to convey that they are below a carrier ring 200. The spiderforks 226, using an engagement and rotation mechanism 220 are configuredto raise up and lift the carrier rings 200 (i.e., from a lower surfaceof the carrier rings 200) from the stations simultaneously, and thenrotate at least one or more stations before lowering the carrier rings200 (where at least one of the carrier rings supports a wafer 101) to anext location so that further plasma processing, treatment and/or filmdeposition can take place on respective wafers 101.

FIG. 3 shows a schematic view of an embodiment of a multi-stationprocessing tool or process module 110 with an inbound load lock 302 andan outbound load lock 304. A robot 131, at atmospheric pressure, isconfigured to move substrates from a cassette loaded through a pod 308into inbound load lock 302 via an atmospheric port 310. Inbound loadlock 302 is coupled to a vacuum source (not shown) so that, whenatmospheric port 310 is closed, inbound load lock 302 may be pumpeddown. Inbound load lock 302 also includes a chamber transport port 316interfaced with processing chamber 102 b. Thus, when chamber transport316 is opened, another robot (not shown, such as robot 312 of a vacuumtransfer module 190) may move the substrate from inbound load lock 302to a pedestal 140 of a first process station for processing.

The depicted processing chamber 102 b comprises four process stations,numbered from 1 to 4 in the embodiment shown in FIG. 3. In someembodiments, processing chamber 102 b may be configured to maintain alow pressure environment so that substrates may be transferred using acarrier ring 200 among the process stations without experiencing avacuum break and/or air exposure. Each process station depicted in FIG.3 includes a process station substrate holder (shown at 318 for station1) and process gas delivery line inlets.

FIG. 3 also depicts spider forks 226 for transferring substrates withinprocessing chamber 102 b. The spider forks 226 rotate and enabletransfer of wafers from one station to another. The transfer occurs byenabling the spider forks 226 to lift carrier rings 200 from an outerundersurface, which lifts the wafer, and rotates the wafer and carriertogether to the next station. In one configuration, the spider forks 226are made from a ceramic material to withstand high levels of heat duringprocessing.

FIGS. 4A-4E are diagrams illustrating the process for determining anoffset from an initial calibrated location of a rotation axis of arotation device within a process module, wherein the offset is caused bya process condition imposed on the process module, in embodiments of thepresent disclosure.

In particular, FIG. 4A illustrates an incoming calibration wafer 405 toa multi-station process module showing the orientation of the incomingcalibration wafer 405 for purposes of determining an offset of arotation axis of a device within the process module 110 that is under aprocess condition, in accordance with one embodiment of the presentdisclosure. In particular, robot 132 is delivering the calibration waferfrom the vacuum transfer module 190 to the process module 110 via thegate valve 180. The calibration wafer 405 is being delivered to thestation 140 closest to the gate valve 180. Station 140 may include apedestal configured for supporting a wafer. The orientation of thecalibration wafer 405 is indicated by the notch 406, wherein in theincoming orientation, the notch 406 is pointed towards the station 140,such that the notch 406 first enters the gate valve or first passesthrough the AWC sensors 410 with the incoming calibration wafer 405.

As previously introduced, process module 110 is configured forprocessing wafers in a vacuum or controlled environment. For example,the process module 110 may be configured to implement one or moresemiconductor manufacturing processes. For example, process module 110includes a multi-station plasma processing chamber for generating plasmato facilitate various processes that include the depositing of amaterial during a deposition or etching process, such as ALD and PECVDprocesses. The chamber may include one or more of electrodes, substratesupport, electrostatic chuck in the substrate support (configured toinclude electrodes biased to a high voltage in order to induce anelectrostatic holding force to hold the wafer in position), one or moregas showerheads, gap control mechanisms, for controlling the gap betweenthe substrate support and the showerheads. For purposes of brevity andclarity, detailed descriptions of the various other components of thechamber and/or process module 110 that are known to those skilled in theart are not provided, but are contemplated and fully supported.

In addition, station 140 may include a lift pad (also referred to astwist pad) configured for rotation. The lift pad is configured to lift awafer off the pedestal 140 and rotate a wafer disposed thereon withrespect the process module 110 and/or the corresponding pedestal 140.For purposes of illustration, the lift pad may be used within processmodules performing ALD and PECVD processes and/or applications. Forexample, one or more motors may be configured to lift a wafer processingpedestal 140 (e.g., function of an existing pedestal-lift device) andalso lift a wafer off the pedestal with a lift pad. In one embodiment,the lift pad is approximately sized to a wafer. In another embodiment,the size of the lift pad is smaller than a wafer. The lift pad may beseparately controlled from the pedestal, such that the lift pad may beseparated from the pedestal for purposes of rotation. For example, uponseparation o of the lift pad from the pedestal, a wafer supported by thelift pad rotates with the rotation of the lift pad. As such, thepedestal 140 and the process chamber or process module enclosing thepedestal remain fixed in relation to the lift pad that is rotating.

In embodiments of the disclosure rotation of the wafer may be performedusing any rotation device located within the process module 110 forpurposes of determining an offset of a rotation axis of a device withinthe process module 110 that is caused by a process condition imposed onthe process module 110. For example, a rotation device may be located onthe end effector of a spindle or spider forks configured to rotate thestations and or pedestals 140 within the process module 110. One type ofspindle may be the rotation mechanism 220 and/or spider forks 226previously introduced in FIG. 2. The rotation device is configured torotate a wafer as the entire spindle normally rotates between thestations 140. For example, the rotation device on the end effector mayrotate a wafer effectively between 0-180 degrees in a clockwise orcounter-clockwise fashion in embodiments, while the spindle istransferring wafers from one processing station to another processingstation (e.g., stations located 90, 180, or 270 degrees apart) within aquad-station or multi-station process module 110. The wafer rotationmechanism and/or device is located concentrically on the spindle endeffector where wafer transfer is being performed.

As shown in FIG. 4A, the gate valve 180 may include active wafercentering (AWC) sensors 410. The AWC sensors 410 are configured toperform intransit wafer position measurement and correction, as will befurther described below in FIGS. 4E, 6A-6B and 7. For example, the AWCsensors 410 may be vertically mounted through-beam sensors. The AWCsensors 410 may be mounted such that their respective beams extend alongthe Z-axis, which is perpendicular to the page of FIG. 4A. As such, AWCsensors 410 detect when their respective beams are broken, such as whenan opaque object (e.g., a wafer or a portion of an end-effector) blockstheir beam. In general, a wafer may trigger the AWC sensors 410 two ormore times as the wafer is in transit (e.g., the wafer may pass throughthe AWC sensors 410 in one direction, or back and forth to increase thenumber of data points). Up to four points on the wafer may be triggeredand used to measure a position/location of the wafer (e.g., a center ofwafer) within a reference coordinate system (not shown). That positionmay be used for alignment correction, and to determine a conditionoffset of the rotation axis of the rotation device within the processmodule 110. For example, the AWC sensors 410 may be part of ameasurement device that is used to measure wafer position relative to acalibration set of data. The calibration set of data generates acalibrated reference measurement that is aligned with an initialcalibrated location of the rotation axis (e.g., during cold set-up).During tool set-up, a wafer is centered onto the pedestal 140 usingcentering techniques (e.g., feature alignment). The calibration wafer405 is picked up by the robot 132, and the calibration wafer 405 ismoved in and out of the process module 110 at full speed, whilerecording the robot location of the calibration wafer within a referencecoordinate system (e.g., wherein the measurement device is fixed withinthe reference coordinate system) when sensor beams corresponding to theAWC sensors 410 are broken. That measurement data is used to determinethe wafer position within the reference coordinate system. Examples ofthe use of AWC sensors for calibrating robots are disclosed in commonlyowned U.S. Pat. No. 6,934,606.

FIG. 4B illustrates an outgoing calibration wafer 405 from themulti-station process module 110 introduced in FIG. 4A showing theorientation of the outgoing calibration wafer 405 for purposes ofdetermining an offset of a rotation axis of a device within the processmodule that is under a process condition, in accordance with oneembodiment of the present disclosure. In particular, robot 132 isdelivering the calibration wafer from the process module 110 to thetransfer module 190 via the gate valve 180. The orientation of thecalibration wafer 405 is indicated by notch 406, which in the outgoingorientation, the notch 406 has been rotated by an angle and is pointedaway from the station 140, such that the notch 406 first enters the gatevalve or first passes through the AWC sensors 410 for the outgoingcalibration wafer 405. That is, between the two orientations of theincoming calibration wafer 405 and the outgoing calibration wafer 405,the wafer has been rotated by approximately 180 degrees. In embodiments,the rotation of the calibration wafer 405 may be an angle between arange that is greater than 0 degrees and equal to or below 180 degreesfor determining the offset of the rotation access of a process moduleunder a process condition. In embodiments, the angle the wafer isrotated can be one of approximately 5, 10, 15, 20, 25, 30, 35, 40, 45,50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125,130, 135, 140, 145, 150, 155, 160, 165, 170, 175, and 180 degrees. Inembodiments, the rotation of the calibration wafer 405 may be aneffective angle defined within an effective range, wherein one range isdefined as being greater than 0 and up to and including 15 degrees,another range is defined as between 5 and 20 degrees, another range isdefined as between 10 and 25 degrees, another range is defined asbetween 15 and 30 degrees, another range is defined as between 20 and 35degrees, another range is defined as between 25 and 40 degrees, anotherrange is defined as between 30 and 45 degrees, another range is definedas between 35 and 50 degrees, another range is defined as between 40 and55 degrees, another range is defined as between 45 and 60 degrees,another range is defined as between 50 and 65 degrees, another range isdefined as between 55 and 70 degrees, another range is defined asbetween 60 and 75 degrees, another range is defined as between 65 and 80degrees, another range is defined as between 70 and 85 degrees, anotherrange is defined as between 75 and 90 degrees, another range is definedas between 80 and 95 degrees, another range is defined as between 85 and100 degrees, another range is defined as between 90 and 105 degrees,another range is defined as between 95 and 110 degrees, another range isdefined as between 100 and 115 degrees, another range is defined asbetween 105 and 120 degrees, another range is defined as between 110 and125 degrees, another range is defined as between 115 and 130 degrees,another range is defined as between 120 and 135 degrees, another rangeis defined as between 125 and 140 degrees, another range is defined asbetween 130 and 145 degrees, another range is defined as between 135 and150 degrees, another range is defined as between 140 and 155 degrees,another range is defined as between 145 and 160 degrees, another rangeis defined as between 150 and 165 degrees, another range is defined asbetween 155 and 170 degrees, another range is defined as between 160 and175 degrees, another range is defined as between 165 and 180 degrees,another range is defined as between 170 and 185 degrees, another rangeis defined as between 175 and 190 degrees.

FIG. 4C illustrates the process of determining an offset of a rotationaxis of a rotation device (e.g., lift pad) within a process module 110that is under a process condition (e.g., high temperature, vacuum, etc.)using measurements of an incoming calibration wafer 405 and an outgoingcalibration wafer 405, as previously introduced in FIGS. 4A-4B, inaccordance with one embodiment of the present disclosure. Embodiments ofthe present disclosure are used to teach a robot (e.g., the TM robot132) to station (e.g., to move to the center of the pedestal 140) whenthe process module 110 is under a process condition. The motioncoordinate system of the TM robot 132 can be a radial (R), theta (T),and vertical (Z), for each arm of the robot 132. Another motioncoordinate system of the TM robot 132 can include an X-axis, a Y-axis,and a Z-axis. Still other coordinate systems are supported. Previously,the challenge in most PECVD or ALD semiconductor processing applicationsis putting any sensors inside of the process module 110, since it isunder high temperatures (e.g., 650 Celsius), and may be under vacuum.That is, the sensors are inoperable when process conditions are imposedon the process module 110. As such, previous to embodiments of thepresent disclosure, the offset to any point in the process module causedby imposing a process condition on the process module could not bedetermined.

Embodiments of the present disclosure take advantage of a rotationdevice within the process module 110 to rotate a calibration wafer 405by an angle (between orientations of an incoming calibration wafer 405and an outgoing calibration wafer 405) and take measurements of theincoming and outgoing calibration wafer 405 using a measurement device(e.g., AWC sensors 410) located outside of the process module 110 inorder to determine the offset of a rotation axis of a rotation devicelocated within the process module 110. Specifically, movement of theincoming calibration wafer 405 (as measured) to the outgoing calibrationwafer (as measured) indicates the offset of the rotation axis of therotation device caused by imposing the process condition on the processmodule 110, as will be further described in FIGS. 6A-6B.

Generally, the incoming calibration wafer 405 offset relative to the AWCcoordinate frame can be measured (e.g., measured offset 420) using theAWC sensors 410 (e.g., measurement #1). For example, the offset ismeasured from a perfectly aligned wafer measurement as defined by theAWC coordinate frame, such as the center of the AWC coordinate frame.The AWC sensors 410 can measure the wafer offset again (e.g., measuredoffset 425) using the AWC sensors 410 on the outgoing calibration wafer405, after rotation of the wafer. That is, the positions of the incomingcalibration wafer 405 and the outgoing calibration wafer 405 at aspecific point in the system (e.g., as the wafer is passing through thegate valve 180 at the AWC sensors 410) is measured against a referencecoordinate frame (e.g., the AWC coordinate frame) established duringtool setup, wherein the reference coordinate frame corresponds to anincoming and outgoing wafer perfectly aligned with an initial calibratedlocation (e.g., teach location) of the center of the pedestal (e.g.,rotation axis) where wafers are to be placed. The difference betweenmeasurements (e.g., the end points of the offsets in the referencecoordinate frame) should only be a result of the “offset waferrotation,” or offset of the rotation axis of the rotation device. Thisdifference may be represented by a vector between the two measuredlocations within the reference coordinate system. Assuming that therotation device has a negligible radial runout relative to their centeraxis (e.g., rotation axis) (e.g., spindle end-effector or center axis oflift pad of a pedestal 140), the differences in the AWC measurementsshould be double the offset of the wafer relative to the pedestal, aswill be further described in FIGS. 6A-6B. This defines the requiredteach position change to handoff wafers centered to the pedestal 140while the process module is under a process condition.

FIG. 4D illustrates an example of calculating an offset correctionvector and/or condition correction vector, in accordance with oneembodiment of the present disclosure. In particular, the offsetcorrection vector in x and y coordinates is based measurements of atleast: an inbound AWC value, and an outbound AWC value.

FIG. 4E is a flow diagram 400E illustrating a method for determining atemperature induced offset of pedestal in a process module that is undera process condition, in accordance with one embodiment of the presentdisclosure. To determine the temperature induced offset, the processmodule is placed under the same process condition used for processingwafers. For example, the process module is placed under the temperatureconditions used when processing wafers. The proper temperature selecteddepends on which process is used. The method in the present disclosureis discussed with reference to specific components of the plasmaprocessing system 100, wherein flow diagram 400E may be implementedwithin the above referenced wafer processing system 100.

At 450, the method includes delivering a wafer to a pedestal of a singleor multi-station process module by a robot, and detecting an entryoffset. The wafer may be a calibration wafer used during calibrationprocedures. The robot may be robot within a vacuum transfer module, suchas robot 132. The pedestal may be configurable as a rotating device,such that the pedestal itself or a component of a pedestal assembly isrotatable. The entry offset is measured from or against a calibratedreference measurement that is defined within a reference coordinatesystem that is based on an initial calibrated location of the pedestalwithin the process module. In particular, the calibrated referencemeasurement defines a perfectly aligned wafer that is entering theprocess module, and is perfectly aligned to be placed to the center ofthe pedestal. The calibrated reference measurement may be determinedwhen the process module is not under a process condition, as will befurther described in relation to FIG. 5A.

At 455, the method includes rotating the wafer over the pedestal by anangle. In particular, the pedestal assembly previously introduced mayinclude a pedestal and a lift pad, wherein the lift pad is configuredfor rotation with respect to the pedestal. For example, the wafer may beplaced on the pedestal assembly. The lift pad is separated from thepedestal, and rotated along or about a rotation axis (e.g., the axisdefining the center of the pedestal), and the lift pad is rotatedrelative to the pedestal between at least a first angular orientationand a second angular orientation defining the angle.

At 460, the method includes removing the wafer from the pedestal by therobot and measuring an exit offset. The exit offset is measured from oragainst the calibrated reference measurement that is defined within thereference coordinate system.

At 465, the method includes determining a magnitude and direction (e.g.,vector components) of the temperature induced offset using the entryoffset and the exit offset. As previously described, the differencebetween measurements (e.g., the end points of the offsets in thereference coordinate frame) should only be a result of the “offset waferrotation,” or offset of the rotation axis of the rotation device. Thisdifference may be represented by a vector between the two measuredlocations within the reference coordinate system. In particular, thetemperature induced offset corresponds to the movement or offset of thecenter of the pedestal from an initial calibrated location (e.g., a coldteach location) when the process module is under the processtemperature. From the difference vector, halving the magnitude of thedifference vector will determine the temperature induced offset of thecenter of the pedestal from its initial calibrated location.Specifically, the mid-point of the vector defines the end point of thetemperature induced offset, with respect to the calibrated referencemeasurement that is aligned (or translated) with the initial calibratedlocation of the pedestal. A temperature correction of the center of thepedestal may be determined based on the temperature induced offset.

With the detailed description of the various modules of the plasmaprocessing system 100 and plasma process modules 110, flow diagrams500A-500C of FIGS. 5A-5C disclose methods for determining calibratedreference measurements, a condition correction of a process module, andan alignment correction of an incoming wafer under process. Method 500Aand the other methods (e.g., methods 400E, 500B and 500C) in the presentdisclosure are discussed with reference to specific components of theplasma processing system 100, wherein flow diagrams 500A-500C areimplemented within the above referenced wafer processing system 100. Forexample, various sensors and components of system 100 are employed tofacilitate calibration of the TM robot 132, and the determination of anoffset of a rotation axis of a rotation device within a process module110.

In particular, flow diagram 500A discloses a method for determining acalibrated reference measurement (e.g., initialized location) of acalibration wafer held by a transfer module (TM) robot as measured by ameasuring device, wherein the location of the calibrated referencemeasurement is aligned with the initial calibrated location of arotation axis of a rotation device within a process module, inaccordance with one embodiment of the present disclosure. Flow diagram500A may be implemented in combination with and may include variousprocesses performed in a calibration of a TM robot 132 of a vacuumtransfer module 190, for example. In particular, flow diagram 500A maybe performed to establish a reference coordinate system typically usedfor aligning incoming process wafers, and also for determining an offsetof the rotation axis of a rotation device within the process module 110.

Though flow diagram is described in relation to TM robot 132 and an AWCmeasurement device (e.g., AWC sensors 410) to determine the offset ofthe rotation axis, other embodiments are well suited to using otherrobots within the plasma processing system 100 of FIG. 1 and othermeasurement systems. For example, aligners coupled to other robotslocated outside of the process module 110 may be used for determiningmeasurements of wafers. That is, the measurements of the positions of awafer may be taken at any point within the plasma processing system 100as long as the robots and/or components of the system 100 have beeninitially setup and calibrated to each other. In that manner, the pathof a wafer delivered through processing system 100 and placed eventuallyat a pedestal center point is known and calibrated. As such, thepedestal center point can be translated to any point along that path andused to create a reference coordinate system.

At 501, the method includes teaching the TM robot 132 to an initialcalibrated location of the pedestal 140. This teaching of the TM robot132 may be performed during setup of the TM robot 132. In particular,the TM robot 132 is calibrated by teaching the robot 132 the center ofthe pedestal 140 of a process module 110, wherein a wafer that isperfectly aligned is placed to the center of pedestal 140 (e.g., thecenter of wafer is aligned with the center of the pedestal). In oneembodiment, the center of the pedestal 140 corresponds to the centeraxis of both the pedestal 140 and the lift pad. FIG. 6A shows theinitial calibrated location 601 of the pedestal 140, which alsocorresponds to the rotation axis of the lift pad. The initial calibratedlocation 601 may also correspond to (e.g., centered with) an initializedcoordinate system 660 that may be translated throughout the plasmaprocessing system 100, such as with the reference coordinate system660′, as described below.

As such, the center axis also corresponds to the rotation axis of thelift pad, which is configured for rotating a wafer with respect to thepedestal 140 and/or the process module 110. The teaching is typicallyperformed when no condition is imposed on or applied to process module110. For example, this would allow the field technician to perform thesetup procedures, such as for the TM robot 132 and other components ofplasma processing system 100. In one exemplary setup process, the fieldtechnician can manually place the end-effector of the TM robot 132 atthe center of the pedestal 140 to calibrate the TM robot 132.

As previously described, once the center axis of the pedestal 140 isdetermined, and the robot is calibrated, a reference coordinate system601′ can be established at any point along a calibrated path that awafer would take to be placed to or remove from the calibrated center ofthe TM robot 132. That is, the reference coordinate system 601′ is basedon the initial calibrated location of the center of the pedestal.

Determination of the calibrated path is further described below inrelation to the TM robot 132, for example. At 503, the method includesplacing the calibration wafer on or within the rotation device (e.g.,lift pad, end-effector of spindle, etc.) within the process module 110and centered to the rotation axis. In one implementation, a calibrationwafer 405 may be placed (e.g., hand placed) to the center of thepedestal 140. For example, the calibration wafer 405 may be placed usingcentering techniques (e.g., aligning with features in the process module110 and/or pedestal 140). As such, the calibration wafer 405 is assumedto be perfectly aligned to the rotation axis of the rotation device(e.g., lift pad).

At 505, the method includes removing the calibration wafer 405 from theprocess module 110 using the TM robot 132. The removal is along acalibrated path, since the wafer is assumed to be perfectly aligned withthe initial calibrated location of the center of the pedestal, and therobot is assumed to follow the same path when removing a perfectlyaligned wafer and/or placing a perfectly aligned wafer to the center ofpedestal 140. For example, FIG. 6A shows state 409B of calibration wafer405 as centered to the initial calibrated location 601 of the rotationaxis of the rotation device (e.g., lift pad). The perfectly alignedcalibration wafer 405 is removed from the process module 110 to state409A along the calibrated path. This removal is shown by double arrow691 indicating an incoming wafer and an outgoing wafer that is perfectlyaligned to the initial calibrated location 601.

At 507, the method includes establishing a calibrated referencemeasurement of the calibration wafer within the reference coordinatesystem using the measurement device. For example, the measurement devicemay be an AWC system including AWC sensors 410. The calibrated referencemeasurement is aligned with the initial calibrated location of therotation axis corresponding to the rotation device (e.g., lift pad). Forpurposes of illustration, the calibrated reference measurement may betaken at a particular location within the measurement device. Forexample, the calibrated reference measurement may be taken when thecalibration wafer that is aligned with the initial calibrated locationof the rotation axis first engages with the AWC sensors 410 along anincoming path. The calibration wafer may be moved back and forth betweenthe gate valve 180 and the transfer module 190 through the measurementdevice (e.g., AWC sensors 410) to gather a calibration set of data. Thecalibrated reference measurement based on the calibration set of datamay be or correspond to center of the calibration wafer 405. Forexample, in FIG. 6A, the calibrated reference measurement 601′ maycorrespond to the center 630A of the calibration wafer 405 in state 409Athat is at the previously introduced particular location within themeasurement device (e.g., first engaging with the AWC sensors 410 alongan incoming path). Further, the reference coordinate system 660′ maycorrespond to (e.g., be centered with) the calibrated referencemeasurement 601′ for purposes of illustration, though the referencecoordinate system 660′ may be centered at any location as long as it isfixed in relation to the initial calibrated location 601 of the rotationaxis and its initialized coordinate system 660.

FIG. 5B is a flow diagram 500B illustrating a method for determining anoffset of a rotation axis of a rotation device (e.g., lift pad ofpedestal 140) located within a process module 110 that is under aprocess condition using the calibrated reference measurement 601′ of thecalibration wafer 405, in accordance with one embodiment of the presentdisclosure. FIG. 5B may be described in conjunction with FIG. 6A thatillustrates the calibrated reference measurement 601′ of a calibrationwafer 405 that is aligned with the initial calibrated location 601 of arotation axis of a rotation device (e.g., lift pad) within a processmodule. In addition, FIG. 6A shows the effect that an offset of therotation axis of the rotation device within a process module 110 has onthe calibration wafer 405 when the calibration wafer is rotated, inaccordance with one embodiment of the present disclosure. By measuringthe effect, the offset of the rotation axis can be determined withoutusing sensors placed within the process module 110.

At 510, the method includes establishing a reference coordinate system660′ based on an initial calibrated location 601 of a rotation axis of arotation device within a process module. The reference coordinate system660′ was established in flow diagram 500A and illustrated in FIG. 6A.

In addition, at 515 the method includes applying a condition to theprocess module 110. The condition may conform with a process conditionimposed on the process module 110 for purposes of performing ALD and/orPECVD processes on wafers 101. For example, the process condition mayinclude an elevated temperature of the process module 110. For example,various processes may be performed at temperatures between 200-650degrees Celsius. Higher and lower temperatures are also contemplated. Inaddition, the process condition may include other elements, such asvacuum pressure, etc. For instance, the process module 110 may be placedunder vacuum and increased temperatures during wafer processing. Theprocess condition may have an effect on one or more points within theprocess module 110. For example, the process condition may move theinitial calibrated location 601 of the rotation axis of the rotationdevice (e.g., lift pad) by an offset 625. That the elements of theprocess condition, taken alone or in combination, may have an effect onthe initial calibrated location 601. For instance, an increase of thetemperature of the process module 110 may move the center of thepedestal, thereby moving the initial calibrated location 601. Inaddition, placing the process module 110 under vacuum pressure may alsomove the initial calibrated location 601. This offset of the initialcalibrated location 601 may be on the order of millimeters or greater,which would have an adverse effect on semiconductor processing.

At 520, the method includes picking up a calibration wafer from aninbound load lock using a transfer module (TM) robot 132 configured totransfer the calibration wafer 405 to the process module 110. Thecalibration wafer need not be perfectly aligned within the TM robot 132and/or the initial calibrated location 601. That is, embodiments of thepresent disclosure are able to determine the offset of the rotation axisusing a calibration wafer 405 that is normally picked up by the robot132 and that may by misaligned from the calibrated reference measurement601′, and measuring a location of the calibration wafer 405 along itsincoming path (without correction for misalignment), rotating thecalibration wafer 405 within the process module, and measuring alocation of the calibration wafer 405 along its outgoing path.

More specifically at 525, the method includes determining a firstmeasurement of the calibration wafer 405 within the reference coordinatesystem using a measurement device when transferring the calibrationwafer to the process module. The measurement device is fixed within thereference coordinate system 660′. For example, the first measurement maybe performed by the AWC sensors 410 when the calibration wafer isincoming into the process module 110 via gate valve 180. The firstmeasurement may be taken with respect to the reference coordinate system660′ (e.g., defines a center of the calibration wafer 405 as measured).Though the first measurement may indicate that the calibration wafer 405is misaligned with the initial calibrated location 601 and/or thecalibrated reference measurement 601′, no correction for misalignment ismade when determining the offset of the rotation axis of the rotationdevice, even though for normal wafer processing, a correction formisalignment is made.

At 530, the method includes handing off the calibration wafer to theprocess module. This may include handing off the calibration wafer fromone or more robots and/or components within the process module 110before reaching its final destination—the rotation device. In addition,the method includes interfacing the calibration wafer 405 with therotation device. For example, the interfacing may include placing thecalibration wafer 405 on the lift pad and pedestal 140. In anotherexample, the interfacing may include picking up the calibration wafer405 by an end effector of a spindle or rotation device 220 configured totransfer wafers from one station to another in the multi-station processmodule 110, wherein the end-effector is configured for rotating a wafer.Still other means for interfacing the calibration to the rotation deviceis contemplated.

At 535, the method includes rotating the calibration wafer 405 by anangle using the rotation device. For example, the rotation device may bea lift pad that is configured for rotating a wafer placed thereon withrespect to the pedestal 140 and/or the process module 110. In oneembodiment, the resulting angle of rotation may effectively be greaterthan 0 degrees to less than or equal to 180 degrees (e.g., clockwise orcounterclockwise) between an incoming orientation of the calibrationwafer 405 (corresponding to the incoming path as placed on or within therotation device) and an outgoing orientation of the calibration wafer(corresponding to the outgoing path as removed from the rotationdevice).

For example, when the rotation device is a lift pad, the method mayinclude placing the calibration wafer 405 on the lift pad of therotation device that is configured for depositing a film on a processwafer. The rotation device includes a pedestal and lift pad assembly,wherein the pedestal has a pedestal top surface extending from a centralaxis of the pedestal. The central axis may also correspond to therotation axis of the lift pad. The lift pad is configured to rest uponthe pedestal top surface, interface with the pedestal top surface,and/or be separated from the pedestal top surface. The method mayinclude separating the lift pad from the pedestal top surface along thecentral axis. The method may include rotating the lift pad relative tothe pedestal top surface between at least a first angular orientationand a second angular orientation defining the angle.

In another example, when the rotation device is an end-effector of aspindle or rotation device 220, the method may include picking up thecalibration wafer from a first station in the multi-station processmodule 110 using an end effector (not shown) of a spindle robot (e.g.,rotation device 220). The spindle robot is configured for transferringwafers between stations in the process module 110, and wherein the endeffector is configured for rotating the wafer. In addition, the methodincludes placing the calibration wafer on the first station for removalfrom the process module after rotation.

At 540, the method includes removing the calibration wafer 405 from theprocess module using the TM robot 132. In that manner, a measurement ofthe calibration wafer 405 may be made outside of the process module 110.In particular, at 545, the method includes determining a secondmeasurement of the calibration wafer 405 within the reference coordinatesystem 660′ using the measurement device when transferring thecalibration wafer to an outbound load lock. For example, the secondmeasurement may be performed by the AWC sensors 410 when the calibrationwafer is outgoing from the process module 110 via gate valve 180. Thesecond measurement may be taken with respect to the reference coordinatesystem 660′ (e.g., defining a center of the calibration wafer 405 asmeasured).

For example, FIG. 6A shows the path of the calibration wafer 405 whendetermining the offset 625 of the rotation axis. For purposes ofintroduction and ease of illustrating the steps used to determine theoffset 625, the incoming calibration wafer 405 is perfectly aligned withthe initial calibrated location 601 of the rotation axis (e.g., centerof the pedestal 140 when setup). Of course, the incoming calibrationwafer 405 need not be perfectly aligned, as illustrated and described inrelation to FIG. 6B, such that no matter the alignment of the incomingcalibration wafer 405 the offset 625 may still be determined throughmeasurement and rotation. As shown, state 409A shows the calibrationwafer 405 along an incoming path that is perfectly aligned with theinitial calibrated location 601. The first measurement corresponds withand/or is translated to the measured center 630A of the calibrationwafer 405 (which when perfectly aligned also corresponds to thecalibrated reference measurement 601′). After the first measurement ofthe calibration wafer 405 is performed, the TM robot 132 transfers thecalibration wafer 405 into the process module, as indicated by arrow691. State 405B of calibration wafer 405 shows the delivery of thecalibration wafer 405 to the station or pedestal 140 which includes arotation device (e.g., lift pad). Since the calibration wafer 405 isperfectly aligned, the center of the calibration wafer 405 is placed tothe initial calibration location 601, which during setup alsocorresponds to the rotation axis of the rotation device (at coldtemperature and at atmosphere). Because the process module 110 is nowunder a process condition, the rotation axis has moved or is offset fromits original location. As shown, rotation axis 650 is offset from theinitial calibration location 601. For example, the entire pedestal andits center axis has moved with respect to the reference coordinatesystem 660′ by an offset 625, and the measurement device that is fixedto the reference coordinate system 660′ and outside of the processmodule 110. As such, the calibration wafer 405 is not centered on thepedestal. State 409C of the calibration wafer 405 shows the rotation ofthe calibration wafer 405 by an angle (e.g., 180 degrees). Afterrotation, the center 630B of calibration wafer 405 moves along line 693.Pre-rotation, the notch 406 is at the top of the calibration wafer 405,and post-rotation, the notch is at the bottom of the calibration wafer405, as shown in FIG. 6A. Calibration wafer 405 pre-rotation is shown bydotted lines, whereas calibration wafer 405 post-rotation is shown bybolded solid lines. State 409D shows the calibration wafer 405 along anoutgoing path when removed from the process module 110. Because of therotation, the outgoing path is no longer perfectly aligned with theinitial calibrated location 601. A second measurement is taken and maycorrespond with and/or may be translated to the measured center 630D ofthe calibration wafer 405.

At 550, the method includes determining a condition correction of therotation axis based on the first measurement and the second measurement.The condition correction corresponds to the offset 625 of the rotationaxis 650 from the initial calibrated location 601 when the processmodule is under the process condition. That is, the offset 625 is causedby the process condition. FIG. 6A shows the offset 625 as a vector thatis determined through the first and second measurements (e.g., themeasured center 630A of the incoming calibration wafer 405 and center630D of the outgoing calibration wafer 405). In particular, thecondition correction may be performed by determining a difference vector620A between the first measurement and the second measurement. That is,the difference vector intersects the measured locations of the centers630A and 630D of the incoming and outgoing calibration wafer 405. Assuch, the difference vector would vary depending on the alignment of theincoming calibration wafer 405. The difference vector 620A is also shownas translated between lines 621 and 623 that are perpendicular to thedifference vector 620A and intersect with respective centers of thecalibration wafer 405 in a pre-rotation state (e.g., center 630B) and ina post-rotation state (e.g., center 630C), as shown by rotation line693.

Further, the offset of the rotation axis from its initial calibratedlocation 601 is determined by halving the magnitude of the differencevector 620A to determine the end point of the offset vector 625. Inparticular, the offset vector 625 may be determined by placing thedifference vector (e.g., 620A) between the measured centers (e.g., 630Aand 630D) of the incoming and outgoing wafers 405 (e.g., the differenceby the measured centers) within the reference coordinate system 660′.Half the difference vector (e.g., halving the magnitude) indicates theend point of the offset vector 625, wherein the start point of theoffset vector 625 corresponds to the calibrated reference measurement601′. In FIG. 6A, because the incoming calibration wafer is perfectlyaligned, the offset vector 625 lies on the difference vector 620A.However, when the incoming calibration wafer 405 is misaligned, theoffset vector 625 would not lie (e.g., have the same direction) on itscorresponding difference vector, as will be shown in FIG. 6B.

As previously described, the determination of the offset vector 625 isnot dependent on perfect alignment of the incoming calibration wafer405. FIG. 6B is a diagram illustrating the determination of the offsetof a rotation axis of a rotation device within a process module byrotating an incoming wafer by an angle by the rotation device, whereinthe determination is alignment agnostic, in accordance with oneembodiment of the disclosure. As shown, four different configurationwafers 405 are shown along four different incoming paths (e.g.,horizontal path perpendicular with x-axis of the reference coordinatesystem 660′). The x-axis of the reference coordinate system 660′ may beconsidered to be perfectly aligned with the initial calibrated location601 along a perfect alignment path. In particular, configuration wafer405A (as also shown in FIG. 6A) is perfectly aligned with the initialcalibrated location 601. That is, the center 630A of configuration wafer405A as determined by a first measurement is perfectly aligned with thecalibrated reference measurement 601′ of the reference coordinate system660′. However, configuration wafer 405B is misaligned as indicated by analignment offset of the center of the wafer 405B, as determined by afirst measurement, from the calibrated reference measurement 601′. Also,configuration wafer 405C is misaligned as indicated by an alignmentoffset of the center of the wafer 405C, as determined by a firstmeasurement, from the calibrated reference measurement 601′.Configuration wafer 405D is also misaligned as indicated by an alignmentoffset of the center of the wafer 405D, as determined by a firstmeasurement, from the calibrated reference measurement 601′.

Each of the first and second measurement pairs for configuration wafers405A-405D in FIG. 6B define difference vectors within the referencecoordinate system 660′. For example, for configuration wafer 405A, firstand second measurements define the difference vector 620A, previouslyintroduced in FIG. 6A. Similarly, difference vector 620B is defined forfirst and second measurements of configuration wafer 405B, differencevector 620C is defined for first and second measurements ofconfiguration wafer 405C, and difference vector 620D is defined forfirst and second measurements of configuration wafer 405D. All thedifference vectors 620A-620D intersect at the end point of the offsetvector 625 at point 650′, which may be a translation of the rotationaxis 650 as offset due to process conditions. That is, for eachdifference vector beginning at its respective first measurement of acorresponding incoming calibration wafer, halving the magnitude alsodefines the end point of the offset vector 625. The start point of theoffset vector 625 is defined by the calibrated reference measurement601′.

For purposes of illustration, any incoming wafer at any point along acalibrated path that is aligned with the initial calibrated location 601may be corrected by the condition correction which corresponds to theoffset vector 625. For example, in FIG. 6A, the calibrated wafer 405 instate 409A that is perfectly aligned to the initial calibrated location601 is not aligned to the rotation axis 650 that has moved due toprocess condition imposed on the process module 110 until after applyingthe condition correction (e.g., offset vector 625). In that manner, theincoming calibration wafer is now aligned with point 650′ which isaligned with the rotation axis 650 in the process module 110. Forincoming wafers misaligned with the reference calibrated measurement601′ and correspondingly the initial calibrated location 601, analignment correction is also applied to bring the wafer into fullalignment with the rotation axis of the rotation device, as will bedescribed in FIG. 5C.

A discussion of the formula for determining a condition offset and itscorrection follows. Variable inputs are described, as follows:X ₁ Y _(Y)=AWC measured offset #1  (1)X ₂ Y ₂=AWC measured offset #2  (2)

Intermediate variables are described, as follows:ΔX _(P) ,ΔY _(P)=Pedestal offset change(with 180 degree rotation)  (3)

Desired outputs are described, as follows:X _(P1) ,Y _(P1)=Offset on pedestal #1  (4)X _(P2) ,Y _(P2)=Offset on pedestal #2  (5)X _(C) ,Y _(C)=Robot Auto-calibration Correction Vector  (6)

Coordinate rotation matrix, 180 degrees (offset wafer rotating onpedestal) is described, as follows:X _(P2) ,=X _(P1)*cos(θ)−Y _(P1)*sin(θ)  (7)Y _(P2) ,=X _(P1)*sin(θ)−Y _(P1)*cos(θ)  (8)

When the angle of rotation (θ) is 180 degrees, values are determined, asfollows:X _(P2) =−X _(P1)  (9)Y _(P2) =−Y _(P1)  (10)

Therefore, the following is defined, as follows:ΔX _(P) =X _(P2) −X _(P1) =−X _(P1) −X _(P1)=−2X _(P1)  (11)ΔY _(P) =Y _(P2) −Y _(P1) =−Y _(P1) −Y _(P1)=−2Y _(P1)  (12)

The AWC measurement reflects pedestal offset change as well, as follows:ΔX _(P) =X ₂ −X ₁=2X _(P1)  (13)ΔY _(P) =Y ₂ −Y ₁=2Y _(P1)  (14)X _(P1)=(½)(X ₂ −X ₁)  (15)Y _(P1)=(½)(Y ₂ −Y ₁)  (16)

The desired robot auto-calibration correction vector is opposite thedirection of the offset, as defined by the following:X _(C) =−X _(P)=(½)(X ₁ −X ₂)  (17)Y _(C) =−Y _(P1)=(½)(Y ₁ −Y ₂)  (18)

An example for calculating the offset correction vector and/or conditioncorrection vector is provided in FIG. 4D.

FIG. 5C is a flow diagram 500C illustrating a method for determining analignment offset of an incoming process wafer from the calibratedreference measurement, and applying an alignment correction based on thealignment offset and a condition correction based on an offset of arotation axis of a rotation device within a process module to theincoming process wafer, in accordance with one embodiment of the presentdisclosure. Flow diagram 500C is performed during processing of wafers,and after calibration of the TM robot 132 as described in relation toFIG. 5A and the determination of the offset of the rotation axis of therotation device as described in relation to FIG. 5B.

At 561, the method includes setting a condition for a process module forpurposes of processing wafers. Previously, a reference coordinate systemwas established that is based on an initial calibrated location of arotation axis of a rotation device within the process module (e.g., asdescribed in relation to FIG. 5A and 510 of FIG. 5B). Also, a calibratedreference measurement (e.g., measurement 601′ of a calibration wafer405) is also established within the reference coordinate system 660using a measurement device that is fixed within the reference coordinatesystem, as previously introduced in FIG. 5A. The calibrated referencemeasurement 601′ is aligned with the initial calibrated location 601, aspreviously described.

At 565, the method includes picking up a process wafer 101 from aninbound load lock 170 using the TM robot. The process wafer is not thecalibration wafer 405 in one embodiment, but a wafer designated toundergo processing of semiconductor devices and/or integrated circuitsof semiconductor devices.

At 570, the method includes determining an alignment measurement of theprocess wafer within the reference coordinate system 660′ using themeasurement device when transferring the process wafer 101 to theprocess module 110. That is, the process wafer as picked up by the TMrobot 132 may not be perfectly aligned to be placed centered with theinitial calibrated location 601 corresponding to the center of thepedestal and rotation axis of the rotation device (e.g., lift pad). Thealignment measurement determines the alignment offset of the incomingprocess wafer 101 as measured with the measuring device (e.g., AWCsensors 410) with respect to the calibrated reference measurement 601′.

For example, FIG. 7 is a diagram illustrating the alignment offset of anincoming process wafer 101 from the calibrated reference measurement601′, in accordance with one embodiment of the present disclosure. Asshown, the calibrated reference measurement 601′ of a perfectly alignedcalibration wafer 405, as measured by the measurement device within thereference coordinate system 660′ and located outside of the processmodule 110, is aligned with the initial calibrated location 601 of thepedestal 140 and/or the rotation axis of the rotation device. Inaddition, process wafer 101 is shown misaligned with the calibratedreference measurement 601′ by an alignment offset 725 (e.g., alignmentoffset vector). In particular, a first measurement (an alignmentmeasurement) of the process wafer 101 is determined by the measurementdevice 610 that is fixed within the reference coordinate system 660′.The alignment measurement may be or be translated to the center 720 ofthe process wafer 101. As shown, the center 720 is misaligned from thecalibrated reference measurement 601′ by the alignment offset 725, whichmay be represented by a vector.

At 575, the method includes obtaining an alignment correction of theprocess wafer corresponding to an offset of the process wafer from thecalibrated reference measurement based on the alignment measurement. Inone embodiment, the alignment correction may be the alignment offsetvector 725.

In addition, a condition correction of the rotation axis may be obtainedat 576. The condition correction corresponds to an offset of therotation axis from the initial calibrated location 601 when the processmodule is placed under a process condition. In particular, the offset ofthe rotation axis is determined before processing based on a rotation ofa calibration wafer 405 by an angle about the rotation axis 650 usingthe rotation device within the process module that is under the processcondition. The condition correction was previously described in relationto FIG. 5B.

In addition, at 580 the method includes applying the conditioncorrection and the alignment correction to the incoming process wafer101 to bring the wafer in alignment with the calibrated referencemeasurement 601′ and correspondingly the initial calibrated location 601of the rotation axis of the rotation device, as previously described.The alignment and condition corrections may be applied to the processwafer using the TM robot 132. Once both the condition correction and thealignment correction are applied, the incoming wafer 101 is aligned whenplacing the process wafer 101 in the process module 110 for processingat 590. That is, the incoming wafer 101 is now aligned to be placed tothe rotation axis of the rotation device that has been offset from itsinitial calibrated location 601 (e.g., the center of the station and/orpedestal 140) within the process module 110 that is under a processcondition.

FIG. 8 shows a control module 800 for controlling the systems describedabove. For instance, the control module 800 may include a processor,memory and one or more interfaces. The control module 800 may beemployed to control devices in the system based in part on sensedvalues. For example only, the control module 800 may control one or moreof valves 802, filter heaters 804, pumps 806, and other devices 808based on the sensed values and other control parameters. The controlmodule 800 receives the sensed values from, for example only, pressuremanometers 810, flow meters 812, temperature sensors 814, and/or othersensors 816. The control module 800 may also be employed to controlprocess conditions during precursor delivery and deposition of the film.The control module 800 will typically include one or more memory devicesand one or more processors.

The control module 800 may control activities of the precursor deliverysystem and deposition apparatus. The control module 800 executescomputer programs including sets of instructions for controlling processtiming, delivery system temperature, and pressure differentials acrossthe filters, valve positions, mixture of gases, chamber pressure,chamber temperature, substrate temperature, RF power levels, substratechuck or pedestal position, and other parameters of a particularprocess. The control module 800 may also monitor the pressuredifferential and automatically switch vapor precursor delivery from oneor more paths to one or more other paths. Other computer programs storedon memory devices associated with the control module 800 may be employedin some embodiments.

Typically there will be a user interface associated with the controlmodule 800. The user interface may include a display 818 (e.g., adisplay screen and/or graphical software displays of the apparatusand/or process conditions), and user input devices 820 such as pointingdevices, keyboards, touch screens, microphones, etc.

Computer programs for controlling delivery of precursor, deposition andother processes in a process sequence can be written in any conventionalcomputer readable programming language: for example, assembly language,C, C++, Pascal, Fortran or others. Compiled object code or script isexecuted by the processor to perform the tasks identified in theprogram.

The control module parameters relate to process conditions such as, forexample, filter pressure differentials, process gas composition and flowrates, temperature, pressure, plasma conditions such as RF power levelsand the low frequency RF frequency, cooling gas pressure, and chamberwall temperature.

The system software may be designed or configured in many differentways. For example, various chamber component subroutines or controlobjects may be written to control operation of the chamber componentsnecessary to carry out the inventive deposition processes. Examples ofprograms or sections of programs for this purpose include substratepositioning code, process gas control code, pressure control code,heater control code, and plasma control code.

A substrate positioning program may include program code for controllingchamber components that are used to load the substrate onto a pedestalor chuck and to control the spacing between the substrate and otherparts of the chamber such as a gas inlet and/or target. A process gascontrol program may include code for controlling gas composition andflow rates and optionally for flowing gas into the chamber prior todeposition in order to stabilize the pressure in the chamber. A filtermonitoring program includes code comparing the measured differential(s)to predetermined value(s) and/or code for switching paths. A pressurecontrol program may include code for controlling the pressure in thechamber by regulating, e.g., a throttle valve in the exhaust system ofthe chamber. A heater control program may include code for controllingthe current to heating units for heating components in the precursordelivery system, the substrate and/or other portions of the system.Alternatively, the heater control program may control delivery of a heattransfer gas such as helium to the substrate chuck.

Examples of sensors that may be monitored during deposition include, butare not limited to, mass flow control modules, pressure sensors such asthe pressure manometers 810, and thermocouples located in deliverysystem, the pedestal or chuck (e.g., the temperature sensors 814/220).Appropriately programmed feedback and control algorithms may be usedwith data from these sensors to maintain desired process conditions. Theforegoing describes implementation of embodiments of the disclosure in asingle or multi-chamber semiconductor processing tool.

In some implementations, a controller is part of a system, which may bepart of the above-described examples. Such systems can comprisesemiconductor processing equipment, including a processing tool ortools, chamber or chambers, a platform or platforms for processing,and/or specific processing components (a substrate pedestal, a gas flowsystem, etc.). These systems may be integrated with electronics forcontrolling their operation before, during, and after processing of asemiconductor wafer or substrate. The electronics may be referred to asthe “controller,” which may control various components or subparts ofthe system or systems. The controller, depending on the processingrequirements and/or the type of system, may be programmed to control anyof the processes disclosed herein, including the delivery of processinggases, temperature settings (e.g., heating and/or cooling), pressuresettings, vacuum settings, power settings, radio frequency (RF)generator settings, RF matching circuit settings, frequency settings,flow rate settings, fluid delivery settings, positional and operationsettings, substrate transfers into and out of a tool and other transfertools and/or load locks connected to or interfaced with a specificsystem.

Broadly speaking, the controller may be defined as electronics havingvarious integrated circuits, logic, memory, and/or software that receiveinstructions, issue instructions, control operation, enable cleaningoperations, enable endpoint measurements, and the like. The integratedcircuits may include chips in the form of firmware that store programinstructions, digital signal processors (DSPs), chips defined asapplication specific integrated circuits (ASICs), and/or one or moremicroprocessors, or microcontrollers that execute program instructions(e.g., software). Program instructions may be instructions communicatedto the controller in the form of various individual settings (or programfiles), defining operational parameters for carrying out a particularprocess on or for a semiconductor substrate or to a system. Theoperational parameters may, in some embodiments, be part of a recipedefined by process engineers to accomplish one or more processing stepsduring the fabrication of one or more layers, materials, metals, oxides,silicon, silicon dioxide, surfaces, circuits, and/or dies of a wafer.

The controller, in some implementations, may be a part of or coupled toa computer that is integrated with, coupled to the system, otherwisenetworked to the system, or a combination thereof. For example, thecontroller may be in the “cloud” of all or a part of a fab host computersystem, which can allow for remote access of the substrate processing.The computer may enable remote access to the system to monitor currentprogress of fabrication operations, examine a history of pastfabrication operations, examine trends or performance metrics from aplurality of fabrication operations, to change parameters of currentprocessing, to set processing steps to follow a current processing, orto start a new process. In some examples, a remote computer (e.g., aserver) can provide process recipes to a system over a network, whichmay include a local network or the Internet.

The remote computer may include a user interface that enables entry orprogramming of parameters and/or settings, which are then communicatedto the system from the remote computer. In some examples, the controllerreceives instructions in the form of data, which specify parameters foreach of the processing steps to be performed during one or moreoperations. It should be understood that the parameters may be specificto the type of process to be performed and the type of tool that thecontroller is configured to interface with or control. Thus as describedabove, the controller may be distributed, such as by comprising one ormore discrete controllers that are networked together and workingtowards a common purpose, such as the processes and controls describedherein. An example of a distributed controller for such purposes wouldbe one or more integrated circuits on a chamber in communication withone or more integrated circuits located remotely (such as at theplatform level or as part of a remote computer) that combine to controla process on the chamber.

Without limitation, example systems may include a plasma etch chamber ormodule, a deposition chamber or module, a spin-rinse chamber or module,a metal plating chamber or module, a clean chamber or module, a beveledge etch chamber or module, a physical vapor deposition (PVD) chamberor module, a chemical vapor deposition (CVD) chamber or module, anatomic layer deposition (ALD) chamber or module, an atomic layer etch(ALE) chamber or module, an ion implantation chamber or module, a trackchamber or module, and any other semiconductor processing systems thatmay be associated or used in the fabrication and/or manufacturing ofsemiconductor wafers.

As noted above, depending on the process step or steps to be performedby the tool, the controller might communicate with one or more of othertool circuits or modules, other tool components, cluster tools, othertool interfaces, adjacent tools, neighboring tools, tools locatedthroughout a factory, a main computer, another controller, or tools usedin material transport that bring containers of wafers to and from toollocations and/or load ports in a semiconductor manufacturing factory.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

Although the foregoing embodiments have been described in some detailfor purposes of clarity of understanding, it will be apparent thatcertain changes and modifications can be practiced within the scope ofthe appended claims. Accordingly, the present embodiments are to beconsidered as illustrative and not restrictive, and the embodiments arenot to be limited to the details given herein, but may be modifiedwithin their scope and equivalents of the claims.

What is claimed is:
 1. A system for processing wafers, comprising: aprocess module including a rotation device having a rotation axis; apedestal within the process module configured for supporting a wafer; atransfer module (TM) robot configured for transferring the wafer to andfrom the process module within a reference coordinate system; and ameasurement system fixed within the reference coordinate system, themeasurement system configured to determine an entry offset of the waferwithin the reference coordinate system when transferring the wafer tothe process module, the measurement system configured to determine anexit offset of the wafer when transferring the wafer from the processmodule and after the wafer has been rotated within the process module bythe rotation device when the process module is under a processcondition, the entry offset and the exit offset being based on aninitial calibrated location of the pedestal in the process module,wherein the measurement system is configured for determining a conditioninduced offset of the rotation axis based on the entry offset and theexit offset.
 2. The system of claim 1, wherein the condition inducedoffset corresponds to an offset of the rotation axis from the initialcalibration location of the pedestal.
 3. The system of claim 1, whereinthe TM robot is configured for applying a condition correction based onthe condition induced offset when transferring a plurality of wafers toand from the process module.
 4. The system of claim 3, wherein themeasurement system is configured for determining an alignment offset ofan incoming wafer based on the initial calibration location of thepedestal, wherein the TM robot is configured for applying the conditioncorrection and an alignment correction based on the alignment offset ofthe incoming wafer.
 5. The system of claim 1, wherein the processcondition includes at least one of a temperature level or a vacuumlevel.
 6. The system of claim 1, wherein the measurement system includestwo sensors configured for detecting the wafer.
 7. The system of claim1, wherein the rotation device is located on an end-effector.
 8. Thesystem of claim 1, wherein the rotation device is a lift pad configuredto separate from the pedestal.
 9. The system of claim 1, wherein therotation device is the pedestal that is configured for rotation.
 10. Thesystem of claim 1, wherein the measurement system is located outside ofthe process module.
 11. A method, comprising: determining an entryoffset of a wafer within a reference coordinate system when transferringthe wafer to a pedestal of a process module, the entry offset beingbased on an initial calibrated location of the pedestal; rotating thewafer within the process module using a rotation device; determining anexit offset of the wafer within the reference coordinate system whentransferring the wafer from the pedestal of the process module, the exitoffset being based on the initial calibrated location of the pedestal;and determining a condition induced offset of a rotation axis of therotation device using the entry offset and the exit offset.
 12. Themethod of claim 11, further comprising: applying a process condition tothe process module.
 13. The method of claim 12, wherein the processcondition includes at least one of a temperature level or a vacuumlevel.
 14. The method of claim 11, further comprising: determining acondition correction for the condition induced offset present when theprocess module is under a process condition.
 15. The method of claim 14,further comprising: applying the condition correction to a robot whentransferring a plurality of wafers to and from the pedestal.
 16. Themethod of claim 11, further comprising: teaching a robot to the initialcalibrated location corresponding to a center of the pedestal when nocondition is applied to the process module; placing a calibration wafercentered to the pedestal; removing the calibration wafer from thepedestal using the robot; defining a calibrated reference measurement ofthe calibration wafer using a measurement device that is fixed withinthe reference coordinate system, the calibrated reference measurementbeing aligned with the initial calibrated location; wherein the entryoffset is measured from the calibrated reference measurement using themeasurement device; and wherein the exit offset is measured from thecalibrated reference measurement using the measurement device.
 17. Themethod of claim 16, wherein the calibrated reference measurement, theentry offset, and the exit offset are located outside of the processmodule.
 18. The method of claim 11, wherein the rotation device islocated on an end-effector.
 19. The method of claim 11, wherein therotation device is a lift pad configured to separate from the pedestal.20. The method of claim 11, wherein the determining the conditioninduced offset includes: determining a difference vector between theentry offset and the exit offset; and halving a magnitude of thedifference vector to determine the condition induced offset of therotation axis of the rotation device.